Influence of competition from nutsedge (Cyperus difformis Blanco), compared with that of barnyardgrass (Echinochloa crus-galli (L.) Beauv.) in transplanted rice (Oryza sativa L.).
Plots were weeded manually every 10 days from the 20th to the 90th day after transplanting rice; in every case the weed regrowth was allowed to compete with the crop. Competition from C. difformis caused yield reductions of 4.5% after 60 days ; yields were reduced by 10% after 50 days in the case of E. crus-galli. Yield losses on the unweeded control were 12% and 45% at the end of the experiment.